Best USB DAC for under $1000

I can't talk to the Gungnir, but I do have the Bifrost with the UBER upgrade - which is basically the single ended output stage from the Gungnir.

The sound is open, spacious, very detailed, dynamic, but most of all very musical.

There is a caveat - both the Gungnir and Bifrost uses the USB power from the computer to power the UCB circuits, but there is a simple solution which I have explained in this post...
Schiit Bifrost with USB & Uber upgrades

Many other USB enabled DACs also use the computers USB power - so it applies to more than the Schiit gear.

You will also find using a good quality power cable like those from AntiCables will make the Gungnir perform to it's highest level.

My Bifrost is now performing very close to my analogue rig, so I'm toying with replacing it with the Gungnir - I've heard it's a little more natural.

Others I've spoken with are very impressed with the Gungnir and if the Bifrost is anything to go by, I can see why

Good luck with your choice

Thanks for the info, but the problem with listening to DAC's in audio stores is that there system will be different then mine.

I have a Tri-Vista 300 Integrated with Infinity MTS Prelude speakers. I will be using a DAC via my HP laptop USB port.Most Audio stores in my area don't stock DAC's under $1K

A used PS Audio PWD2 if you can stretch your budget a few hundred dollars.

if you have a few of the DACs you can bring them to one store and listen to them. Also, most stores will let you bring them home for a bit to hear them in YOUR system. I usually do that unless I know the store's system really good.

The Peachtree is a great way to go.
If you can stretch it a little bit, you might check out the BMC PureDAC.
The good news is, 14 years ago there was a huge disparity in DA performance. Now the playing field is largely even, and a $1,000 unit is better than the earliest $10,000 unit :)